OBJECTIVES: 1. Characterization of physical and chemical differences between purified wild type VSV particles and those of mutants which contain lesions in one of the two envelope proteins--either the internal protein M (group III mutants) or the external glycoprotein G (group V mutants). The content of sialic acid in the G proteins of group V mutants will be determined, and the effect of changes in sialic acid composition on electrophoretic mobility (measured by Doppler shift laser electrophoresis) and thermolability will be assessed. 2. The membrane mutants will be used, in conjunction with fluorescent antibody labelling techniques, to determine the initial events of viral entry into the host cell to initiate infection, and final events of viral organization and budding from the host cell. BIBLIOGRAPHIC REFERENCE: Rothman, J.E. and Lenard, J. "Membrane Asymmetry", Science 195, 743-753 (1977).